Cracking of hydrocarbons



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Unite States Patent Office Reissued Aug. 7, 1962 25,220 CRACKING FHYDROCARBONS .l ack M. Andrews, Highland Park, NJ., and Hampton G.Corneil, Nick P. Peet, and William K. Roquemore, Baytown, Tex.,assignors, by mesne assignments, to Esso Research and EngineeringCompany, Elizabeth, NJ., a corporation of Delaware Original No.2,881,129, dated Apr. 7, 1959, Ser. No. 355,022, May 14, 1953.Application for reissue Oct. 12, 1960, Ser. No. 62,315

Claims. (Cl. 208-120) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

The present invention is directed to an improved method for crackinghydrocarbons. More particularly, the invention is directed to crackinghydrocarbons in a suspension of finely divided catalyst in saidvaporlzed hydrocarbons. In its more particular aspects, the invention isdirected to cracking of hydrocarbons under contacting conditions with afinely divided catalyst which gives substantially improved andunexpected results.

The present invention may be briey described as involving a method ofcracking hydrocarbons in which a iincly divided cracking catalyst isformed into a suspension in admixture with a vaporized hydrocarbon. Thesuspension is then flowed at a gas velocity in the range between about 8and 50 feet per second through an elongated reaction zone having alength to diameter ratio in the range from about 4:1 to about 20:1. Asufficient amount of catalyst is maintained in suspension to provide aweight ratio of feed per hour to catalyst in the reaction zone in therange from about :1 to about 300:1. Under these conditions, thehydrocarbons are cracked to desirable products with formation of aminimum amount of carbonaceous material and carbon laid down on thecatalyst. It is contemplated that the desirable products will beseparated from the catalyst and the catalyst regenerated in a burning orcombustion operation and the regenerated catalyst then employed again toform the suspension in admixture with the vaporized hydrocarbon.

The cracking reaction may take place at a temperature in the range fromabout 800 to about 1100 F.; a preferred range is from about 900 to about1000 F. with quite desirable results being obtained at about 930 F.

Pressures employed in the improved cracking operation may range fromabout atmospheric pressure to about 50 p.s.i.g. (pounds per square inchgauge) with a preferred range of pressures from about 20 to about 35p\.s.1.g.

The improved results of the present invention are obtained by owing thesuspension through the reaction zone at a superficial gas velocity inthe range between about 8 and about 50 feet per second. It isundesirable to ow the suspension at a superficial gas velocity less thanabout 8 feet per second and the preferred range is from 8 feet persecond to about 20 feet per second. Desirable results may be obtained inthe range from about 10 to about 15 feet per second.

The reaction zone employed in the present invention is anv elongatedreaction Zone having a length to diameter ratio in the range from about4:1 to about 20:1. Desirable results are obtained in a verticalelongated reaction zone having a length to diameter ratio of about 7: 1.The Y reaction zone is preferably a vertical elongated reaction zone.

Also to obtain the beneficial results of the present invention, it isnecessary to maintain in the reaction zone an amount of catalystsuflicient to provide a weight ratio of hydrocarbon per hour to catalystin the reaction zone in the range from about 20:1 to about 300: 1. Verygood results may be obtained with a weight ratio of feed per hour tocatalyst in the reaction zone in the range from about 70:1 to about250:1.

Too, desirable results may be obtained by maintaining the catalyst ratein the operation depending on the velocity in the range of 8 to 50 feetper second in a maximum amount of 1 ton per second for the-minimumvelocity and a maximum amount of about l2 tons per seconc for themaximum velocity. AAt a velocity of about 2( feet per second thecatalyst rate would be maintained u1 to about 4.5 tons per second. Thus,the catalyst loadin; in the reaction zone may be expressed by pounds pesquare foot. This may be expressed as catalyst loadin; in the reactionzone, and should not exceed 36 pound per second per square foot for agas velocity in feet pe second of 8, and should not exceed pounds persec ond per square foot for a gas velocity in feet per seconl of 2O orabout 540 pounds per second per square foc at a gas velocity in feet persecond of about 50. Employ ing these conditions, it is possible toobtain the bene iicial results of the present invention.

The feed stock employed in the present invention i preferably a gas-oilhydrocarbon such as one obtaine from crude petroleum. However, othergas-oil fractior may be used. For example, the heavy oil produced i thecracking operation or unconverted portions of th feed stock may form acomponent of the Vreaction feet It is also contemplated that gas-oilsproduced from the: mal cracking operations may suitably be charged totl: process of the present invention. It is contemplated th: residualcrude pertroleum fractions may be charged t the feed stocks to theprocess of the present inventio: The present invention may utilize asfeed hydrocarbc the cracking stocks now used in either thermal or catlytic cracking of hydrocarbons and thus may encompa a wide range of feedstocks. Under some conditions, may be desired to `crack lighterfractions such as tho in the heavy naphtha and kerosene boiling range,say, fro about 400 to about 750 F. Solvent extracts contai ing largepercentages of aromatic hydrocarbons may al form the feed stock to thepresent invention. Crude re dues remaining after removal of valuablelubricating 1 and other fractions may be charged to the process thepresent invention.

The invention will be further illust-rated by referen to the drawing inwhich the single figure is a flow d: graml of a preferred mode ofpracticing the inventir Referring now to the drawing, numeral 11designates charge line through which a gas-oil fraction is introduc intothe system from a source not shown. This gasfraction passes through heatexchanger 12 wherein picks up heat -by heat exchange and is heatedv totemperature of about 450 F, The heated gas-oil th is discharged fromheat exchanger 12 by way of line and may -be split into two streams, onestream flowi by way of line 14 into a furnace 15 containing a coilwherein the temperature of the gas-oil is raised to temperature of about840 F. The otherV stream is flovi by way of line 17 into the lowerportion of a vapori drum 18. The preheated stream from furnace 15 flc byline 19 also into vaporizer 18 at a point in the loi section ofvaporizer 18 but above the point where stream from line 17 isintroduced.

The relative amounts of streams introduced by 1i 17 and 19 are in theapproximate ratio of about 1:6,

In vaporizer "1S, conditions may approximate a te perature of 825 F. anda pressure of about 40 p s. Under these conditions, there is removedfrom thev top vaporizer 18 by way of line 20 a vaporous fraction, zthere is removed from the bottom of vaporizer 18 by l 21 a liquidfraction.

The vaporous fraction in line 20 is routed thereby i D conduit where itis admixed with a finely divided acking catalyst which is introducedfrom conduit 22, ntrolled Iby a valve 23. In conduit V10, the finelydiied catalyst is formed in a suspension in the vaporous cam introducedby line 20, and the suspension is then `wed into the lower end of avertical elongated reacn zone 24. At the entrance to the verticalelongated action zone '24, the suspension has added to it the uid streamfrom line 21, and downstream from the int of addition of the liquidstream there is added to suspension a liquid hydrocarbon feed introducedby e 25 from a later stage in the process, which will be scribed in moredetail hereinafter. [f desired and as iniiuenced by the volatility orother iracteristics of the feed stock, the feed stock may be -passedaround the vaporizer 18 through line 3G conlled by valve 81. Whenoperating in this manner, feed may be routed through furnace by line 14l branch line 83, valve 82 being opened and valve 84 line 17 and valves85 and 87 being closed. Alternazly, the feed stock may be routed throughline 17 and nch line 86 which connects intoline Si) by opening ves 84and closing valves 82 and 85, valve 87 reining closed. When passing aliquid feed stock through z 20 the heat for vaporization of the feedstock is vided by the hot catalyst when the two are adrniXed line 10.The suspension then carrying the liquid stream introed -by line 10 andthe liquid hydrocarbon feed introed by line flows upwardly throughreaction zone Of course, it is understood that the liquid hydrocarlstreams introduced by lines 21 and 25 under the conons prevailing in thereaction zone 24 also become orized. Operations may be conducted inreaction zone to maintain a temperature of about 930iD F., a press ofp.s.i.g., and the suspension may contain about :ons of catalyst. rfterpassage through the elongated reacti-on zone 24, several hydrocarbon-streams introduced therein have u substantially cracked to desirableproducts which contained in the suspension. This suspension conng thedesirable products flows by way of a conduit into a catalyst vessel 27which is provided with an er section 28, which may be termed a spentcatalyst ion, and a lower section 29, which may be termed a lyststripper section. he suspension containing desirable products is intro-:d into the vessel 27 through a distributor box 30 :h is provided with ariser 31 which allows the cataand vaporized products to dischargeupwardly into on 28 and also allows the products and suspension edischarged downwardly into section 29.' The upper on 28 is provided withat least a separating means 1h may be a plurality of cyclones 32, whichare well vn to the art. These cyclones 32 may be intercon- :d to allowthe gases and desirable products to iiow l the lower of the cyclonessequentially through the )nes to insure maximum seperation of theproducts l the catalyst. The cyclones are provided with dip 33 whichdischarge the catalyst downwardly in the :l 27 and specifically into thesections 28 and 29. catalyst separated from the desirable products flowsiwardly in stripper 29, which is provided with a plu- J of baffle plates34 which insures contact of the catawith stripping -steam or a strippinggas which is duced into the section 29 by line 35 through mani- 36. Thesteam flowing countercurrently to the deling catalyst removesvolatilizable carbonaeeous mafrom the catalyst which flows downwardly inthe yst stripper section 29 and outwardly therefrom [gh the cone-shapedsection 37 into a conduit 38 olled by a valve 39. The conduit 38connects into a verse conduit 40 which is provided with line 41, zghwhich air is introduced into conduit 40a The icks up the strippedcatalyst and discharges it by 35 volatilizable carbonaceous material andcoke.

Inented by air introduced into react-ion zone 41 35 separation meansillustrated 10 rality of distillation towers which may be 4shown forconvenience as a single distillation tower.

Fractionation zone 43 may operate at a top temperature of about 275 F.and a bottom temperature of about 700 F. A pressure of about 22 p.s.i.g.may be main- 15 tained on the fractionation zone 43.

Under these conditions, there may be removed from zone 43 by line 44 afraction containing gaseous materials and the lighter fractions such asthe desirable vaporous hydrocarbons having three or rnore carbon atomsin the 20 molecule. For example, the stream withdrawn by line 44 maycontain propane, propylene, butanes, and butylenes and the higherboiling hydrocarbons. 'This stream also contains the desirable crackedgasoline which may be suitably recovered. The stream in line 44- ispassed 25 through a condenser and cooler 45 and then discharged by line46 to stablization and recovery facilities not shown. A heating oilfraction may be withdrawn from fractionation zone 43 by line 47, andlight and heavy cycle gas-oil fractions may be withdrawn from zone 43 30by lines 48 and 49, respectively. A heavier fraction is withdrawn fromzone 43 by line Sil which connects into line 25 and forms a source forthe feed hydrocarbon introduced by line 2S into Zone 24. During thecracking operation in zone 24 there is laid down on the catalyst Thismaterial, if allowed to remain on the catalyst, would impair thecracking operation; however, it is desirable to have a small amount ofcoke or carbonaceous material on the catalyst since this allows the heatnecessary for the proc- 40 ess to be obtained at least in part byburning this material from the catalyst. It is nessary to remove thismaterial from the catalyst to regenerate saine and to allow reuse of thecatalyst in the cracking operation. To this end, the air introduced intoline 4t) by line 41 is suppleby line 53 connecting to a compressor orsome other source of air. By controlling the oxygen content of the airor other free oxygen containing gas introduced into regeneration zone41', it is possible to conduct a combustion or burning operation inregeneration zone 41 such that catalyst is substantially freed ofunstrippable` carbonaceous material and coke and then may ybe reused inthe process. For example, the 4regenerator 41' may contain about 100tons of catalyst which is contacted with about 47,000 standard cubicfeet of air per minute causing cornbustion of the combustible materialon the catalyst. The other conditions for maintenance for the combustionoperation may be a temperature of about 1100 F. and a pressure of l1p.s.i.g.

The regenerated catalyst in a suspension of the combustion products thenflows from regeneration Zone 41 by way of line 54 into a regeneratedcatalyst vessel 55 through a distribution box 56.

The regenerated catalyst vessel 55 is provided with by cyclones 57 whichrnay be arranged for sequential flow of the suspension therethrough toobtain maximum separation of catalyst from the combustion production,which may be termed ue gas. The cyclones 57 are provided with dip legs58 which discharge the separated catalyst back into the vessel 55. Thisvessel may contain catalyst at a temperature of about 1125 F. and is ofa suitable size to provide storage for about 50` tons of regeneratedcatalyst. Air may be introduced into the Ivessel 55 Iby line 59.

Conduit 22 withdraws the catalyst from the vessel 55 yfor introductioninto conduit 21, as has been described, while conduit 60 controlled byvalve 61 provides recycle of catalyst from vessel 55 into regenerator41. Conduit 60 connects into a conduit 62, into which is introduced byline 63 a sufficient amount of air to carry the catalyst from conduit`60 through conduit 62 into vessel 41. The amount of air introduced byline 63 supplements the air introduced by lines 41 and 53.

The combustion products or iiue gas from which catalyst has beenseparated by cyclones 57 in vessel 5S is withdrawn from vessel 55 byconduit 64, which is provided with a Waste heat boiler 65 which may be abank of tubes surrounding or arranged in the conduit 64. The waste heatboiler 65 recovers some of the heat contained in the lflue gas which maybe at a temperature of 1,000" F. The flue gas then iiows into cyclones66 which serve to remove catalyst fines not removed by cyclones 57 `fromthe combustion products. These catalyst fines may have particlediameters in the range from about 0 to 20 microns. The separatedcatalyst fines are discharged from cyclones 66 by way of line '67 into aline 63, and the disposition of these ines will be described furtherhereinafter.

The flue gas substantially free of catalyst nes but containing a smallamount thereof is then routed by conduit 69 into electricalprecipitators 70, which may be of a conventional type where the residualamount of nes is substantially removed from the flue gas. These finesare discharged by line 71 into line l68. Air may be introduced into line68 by line 72 in an amount sulficient to transport the nes toregenerator 41.

A ilue gas substantially free of fines is then discharged into theatmosphere by way of a conduit 73 which connects into a stack 74. It isnot practical to separate completely all of the lines from the flue gas,and a minimum amount of catalyst fines may be discharged through stack74. In fact, it may be desirable to` discharge a minimum amount ofcatalyst fines, since discharge of a small amount and replacementthereof with fresh catalyst serves to maintain the activity of thecatalyst at a high level.

By Virtue of an operation as described in connection with the drawing,it is possible to achieve substantially improved and unexpected resultsin cracking hydrocarbons. Thus, with the present invention, it ispossible to conduct a cracking operation at high efficiencies with thelaying down of less coke ou the -catalyst than is possible inconventional operations. It is possible to produce substantiallyappreciated amounts of gasoline hydrocarbons without impairment of theamount of desirable butanes and butylenes.

Also in the practice of the present invention, it is possible to charge-a substantially greater amount of feed stock to the system than waspossible in conventional operations. Thus, in the improved process it ispossible to increase the throughput by 50% while maintaining the samedegree of conversion or, alternatively, the degrec of conversion may beincreased with the same charge rate. This is accomplished at a lowertemperature with less catalyst and with less formation of coke than wasobtained inl conventional operations.

While the reaction Zone 24, as shown in the drawing, provides for upwardflow of the suspension of catalyst in hydrocarbon, the beneiicialresults of practicing the present invention may also be obtained whenthe catalyst and reactants are flowed downwardly in the reactor. Toaccomplish downward flow, suitable special rearrangement of theapparatus elements in the catalyst cycle may be required.`

In a specic commercial operation, a gas-oil 4fraction may be dividedinto a vapor feed and a liquid feed and the vapor feed admixed withcatalyst to form a suspension. The liquid feed is then mixed with thesuspension, and the admixture has added to it a recycle `feed such asone obtained `from line 50 in the drawing. This suspen sion may then beoWed to a vertical elongated re action zone having an overall length ofyabout 55 fee and having internal diameter for 35 feet of its lengtl ofabout 8 feet, which tapers for its lower 20 feet o length down to about6 lfeet internal diameter. Th suspension is flowed through the reactionzone at superficial gas velocity of about ll feet per second, catalystto oil ratio of about 4.6 and a weight ratio o feed per hour per poundof catalyst in the reactor o about 77. Operating at 54% conversion onthe feed a 930 F. gave substantially improved results. Thus, carbonreduction of 24% was obtained at 10% recycl of fraction such as in line50, while charging about 51,00I barrels per day of fresh feed. Theseresults are sub stantial improvements and allow the production of substantially increased amounts of valuable products ove that possibleheretofore.

The catalyst employed in the practice of the presen invention may be asilica-alumina catalyst having par ticle diameters in the range fromabout 0` to about l0 microns with a major amount of the catalyst havinparticle diameters in the range from about 20 to abou S0 microns.

While it is preferred to -use silica-alumina catalyst, th invention maybe practiced with silica-magnesia catalys silica-zirconia catalyst andmany other nely divide cracking catalysts known to the art.

The catalyst particles suitably may have a specific grai ity in therange of about'1.6 to about 2.73 with a prf ferred specific gravity inthe range from about 1.92 1 about 2.40. v

The nature and objects of the present invention havin been completelydescribed and illustrated, what we -wis to claim as new `and useful andsecure by Letters Pater 1. A method `of cracking hydrocarbons which conprises forming a suspension of a finely divided crackin catalyst havinga specific gravity in the range betwee about 1.6 and about 2.73 in avaporized hydrocarbo feed at a temperature in the range between 800- an1100 F., flowing said suspension aty said temperatur at a gas velocityin the range between about 8 and abol 50 feet per second through saidvertical elongated reactie zone having a length to diameter ratio in therange fro] about 4 to 1 to about 20 to 1, maintaining a suiciei amountof catalyst in said suspension to provide in saiI reaction zone a weightratio of -feed per hour to cataly in the range from about 20 to 1 toabout 300 to 1 1 crack said hydrocarbon feed to desirable products, arrecovering said products.

2. A method of cracking hydrocarbons which con prises forming asuspension of a finely divided crackir catalyst having a specificgravity in the\range betwee about 1.6 and about 2.73 in a vaporizedhydrocarbc feed at a temperature in the range between 800 ar l F., oneof the components of said suspension hal ing its direction of flowchanged immediately prior being formed into said suspension, flowingsaid suspe: sion at said temperature at .a gas velocity in the ran;between about 8 and about 50 feet per second throng a vertical elongatedreaction zone having a length diameter ratio in the range from about 4to 1 to abo' 20 to l, maintaining a suihcient amount of catalyst saidsuspension to provideV in said reaction zone a weig ratio of feed per4hour .to catalyst in the range fromy abo 20 to l to about 300 to l tocrack said hydrocarbon fe to desirable products `and to lay down on saidcataly carbonaceous material and coke, separating catalyst co tainingcarbonaceous material and coke from said d sirable products, recoveringsaid products, admixing sa separated catalyst containing carbonaceousmaterial ai coke with a free `oxygen-containing gas in an amount stcient to support a combustion operation and to form suspension of saidcatalyst containing coke and c: bonaceous material, burning carbonaceousmaterial ai '7 ke from said catalyst in said suspension of said nelyIided catalyst in said free loxygen-containing gas to reuerate same, andseparating combustion reaction prodts from said regenerated catalyst. 3.A method of cracking hydrocarbons which cornses introducing a liquidhydrocarbon feed into a stream hot, finely divided cracking catalysthaving a specific tvity in the range from about 1.6 to about 2.73,vaporng said liquid hydrocarbon feed to form a suspension said finelydivided catalyst in vapors of said hydrobon feed at a temperature in therange between 800 d 1100 F., one of the components of lsaid suspensionving its direction of flow changed immediately prior being formed intosaid suspension, flowing said susision at said temperature at a gasvelocity in the range '.ween about 8 and about 50 feet per secondthrough vertical, elongated reaction zone having a length to meter ratioin the range from about 4: 1 to abo-ut 20: 1, ,intainiug a sufficientamount of catalyst in said suslsion t-o provide in said reaction zone aweight ratio feed per hour to catalyst in the range from about 20:1about 300:1 to crack said hydrocarbon feed to desire products and to laydown on said catalyst cariaceous material and coke, separating catalystcontaincarbonaceous material and coke from said desirable lducts,recovering said products, admixing said sepaed catalyst containingcarbonaceous material and coke h a free oxygen-containing gas in anamount sufent to support a combustion operation and to form a pension ofsaid catalyst containing coke and carlaceous material, burning saidcarbonaceous material l coke from said -catalyst in said suspension ofsaid :ly divided catalyst in said free oxygen-containing gas regeneratesame and separating combustion reaction ducts from said regeneratedcatalyst. A methodof cracking hydrocarbons boiling in the ge from 400 to750 F. which comprises vaporizing l hydrocarbons, forming a suspensionof a rrely ided silica-alumina cracking catalyst having a specific vityin the range between about 1.6 and about 2.73 in l vaporizedhydrocarbons at a temperature in the range veen 800 and 1100 F., one ofthe components of l suspension having its direction of iiow changedimiiately prior to being formed into said suspension, ing to saidsuspension a liquid stream of hydrocarbons ained from a later stage inthe process, flowing said Jension at a temperature in the rang-e between800 1100 F. at a gas velocity in the range between about nd about 50feet per second through a vertical elon- :d reaction one having a lengthto diameter ratio of ut 4 to 1 to abo-ut 20 to 1, maintaining asuflicient )unt of said catalyst in said suspension to provide in lreaction one a weight ratio of feed per hour of Llyst in the range fromabout 20 to 1 to about 300 to i crack said hydrocarbon to desirableproducts, sepang said Idesirable products from said catalyst, and)vering from said products desirable hydrocarbons and liquid stream ofhydrocarbons which is admixed 1 said suspension. Y A method inaccordance with claim 4 in which the ly divided silicaalumina catalysthas particle diams in the range from about to about 100 microns. Aprocess for cracking a gas-oil which comprises ng said gas-oil to atemperature in the range from ut 400 to about 900 F., separating saidgas-oil into rajor quantity of a vaporous fraction and a minor utity ofa liquid fraction, admixing a finely divided a-alurnina catalyst havinga specific gravity in the ge between -about 1.6 and about 2.73 in saidvaporous tion to form a suspension, admixing said liquid fracwith saidsuspension and adding to said suspensionnstream from the addition ofsaid liquid fraction a id hydrocarbon feed obtained from a later stageof process, one of the components of said suspension ing its directionof flow changed immediately prior to being `formed into said suspension,flo-wing said sus'- pension containing said liquid fraction and saidliquid hydrocmbon at a temperature in the range between 800 and 1100 F.at a gas velocity in the range between about 8 and about 50 feet persecond through a vertical elongated reaction zone having a length todiameter ratio in the range from about 4 toll to about 20 to 1,maintaining a sutlicient amount `of catalyst in said suspension toprovide in said reaction zone a weight ratio of feed per hour tocatalyst in the rangefrom about 20 to 1 to about 300 to 1 to crack saidgas-oi1 to desirable products, separating said desirable products fromsaid catalyst, recovering at least a first fraction from said desirableproducts and at least said liquid hydrocarbon feed which is admiXed withsaid suspension, and regenerating the catalyst separated from saiddesirable products.

7. A process for crackin-g a gas-oil which comprises heating saidgas-oil to a temperature in the range from about 400 to about 900 F.,separating said gas-oil into a major quantity of a vaporous fraction anda minor quantity of a liquid fraction, adrnixing a finely divided4silica-alumina catalyst having particle diameters in the range yfromabout 0y to 100 microns and having a specific gravity in the rangebetween about `1.6 and about 2.73 in said vaporous fraction to form asuspension adrnixing said liquid fraction with said suspension andadding to said suspension downstream from the addition of said liquidfraction a liquid hydrocarbon feed obtained from a later stage of theprocess, one of the components of said suspension having its directionof iiow changed immediately prior to being formed into said suspension,iiowing said suspension containing said liquid fraction and said liquidhydrocarbon at a temperature in the range between 800 and 1l00 F. at agas velocity in the range between abont 8 and about 20 feet per secondthrough a Vertical elongated reaction Zone having a length to diameterratio in the range from about 4 to 1 to about 20 to 1, maintaining asufficient amount of catalyst in said suspension to provide in saidreaction zone a weight ratio of feed per hour to catalyst in the rangefrom about 20 to 1 to about 300 to 1 to crack said gas-oil to desirableproducts, separating said desirable products from said catalyst,recovering at least a first fraction from said desirable products and atleast said liquid hydrocarbon feed which is adrniXed with saidsuspension, regenerating the catalyst separated from said desirableproducts, and admixing said regenerated catalyst with the vaporousfraction to form said suspension.

8. A method of reaction hydrocarbons which cornprises forrning asuspension of a nely divided catalyst having a specific gravity in therange between about 1.6 and about 2.73 in a vaporized hydrocarbony feedat a temperature in the range :between 800 and 1100 F., one of thecomponents of said suspension having its direction of flow changedimmediately prior to being formed into said supension, iiowing saidsuspension at said ternperature at a gas velocity in the range betweenabout 8 and about 50 feet per second through a vertical elongatedreaction Zone having .a length to diameter ratio in the range lfromabout 4 to 1 to about 20 to 1, maintaining a suicient amount of catalystin said suspension to provide in said reaction zone a weight ratio offeed per hour to catalyst in the range from about 20 to l to about 300lto 1 to react said hydrocarbon feed to form desirable products, andrecovering said products.

9. A method of cracking hydrocarbons which com* prises forming asuspension of a nely divided cracking catalyst having a specific gravityin the range between about 1.6 and about 2.73 in a vaporized hydrocarbonfeed at a temperature in the range between 800 and 1l00 F., one of thecomponents of said suspension having its direction of flow changedimmediately prior to being for-med into lsaid suspension, flowing saidsuspension downwardly at said temperature at a gas velocity in the rangebetween about 8 and about 50 lfeet per second through a verticalelongated reaction zone having a lengthV 14. In the invention defined inclaim 1, the further in to diameter ratio in the range rfrom about 4 to1 to about provement which comprises introducing a separate liqu. 20 to1, maintaining a sufficient amount of catalyst in hydrocarbon feed intothe suspension of vaporized hydn said suspension to provide in saidreaction zone a Weight carbon feed and finely divided cracking catalyst.

ratio of feed per hour to catalyst in the range from about I5. In theinvention defined in claim 1, the further in 2() to 1 `to about 300 to 1to crack `said hydrocarbon feed prox/ement which comprises introducing aliquid cycle c to desirable products, and recovering said products.fraction obtained from the cracked products 'into the su l0. A method inaccordance With claim -1 in Which pension of vaporized hydrocarbon feedand finely divide the direction of ow of the hydrocarbon is changed.cracking catalyst.

11. A method in accordance With claim 1 in which l() the direction of owof the finely divided catalyst is References Clted m the me of duspatent or the original patent changed.

12. A method in accordance with claim 1 in Which the l UNITED STATESPATENTS specific gravity is in the range between about 1.92 and2,312,230 Belchetz Feb. 23, 19A about 2.40, the gas velocity is in therange betvven about 15 2,351,793 Voorhees June 20, 191 8 feed and about2O Afeet per second, the length to diam- 2,374,073 Belchetz Apr. 17, 194eter ratio is about 7 to 1 and the Weight ratio of feed 2,378,542Edmister June 19, 19 per hour to catalyst is in the range from about 7Gto 1 2,395,109 Martin Mar. 5, 19A to about 250 to 1. 2,427,341 AltherSept. 16, 19 13. A method in accordance with claim 1 in which the 202,487,065 Milliken Nov. 8, 19

length to diameter -ratio is about 7 to l. 2,766,184 Blandng Oct. 9, 195

